micah Posted November 6, 2006 Report Share Posted November 6, 2006 Hi all,i am the proud owner of a new MBSID phase 1. I actually used a 16V AC power adapter to power the core and now my 7805 is burning HOT! My question is this: How hot is too hot? At present, it's too hot to touch and I can feel the heat if I put my hand about 6 inches away.What can I do to eliminate and/or reduce this heat dissipation? Another regulator? Another power supply (maybe 14V?)Thanks! Quote Link to comment Share on other sites More sharing options...
audiocommander Posted November 6, 2006 Report Share Posted November 6, 2006 You shouldn't power the Core with more than 9 V.Best is 7 V.I think you are a lucky man, if you didn't burn something ;)Cheers,Michael Quote Link to comment Share on other sites More sharing options...
stryd_one Posted November 6, 2006 Report Share Posted November 6, 2006 From the IRC chat we're having about your question right now:"How hot is too hot?""Too hot, is when it's hotter than it should be, because you fed it more voltage than it needs" ;)Another reg will introduce noise (so they say, I never tried it)You could strap a heatsink to it but that's a bit of a cop-outYou really should match the voltage better... Quote Link to comment Share on other sites More sharing options...
micah Posted November 6, 2006 Author Report Share Posted November 6, 2006 maybe I misunderstood then. Why does everything I read say to power with a 14-15V AC psu (if not using the original)??? :-[ Quote Link to comment Share on other sites More sharing options...
audiocommander Posted November 6, 2006 Report Share Posted November 6, 2006 from http://www.ucapps.de/mbhp_sid.html"The module requires a second power supply which delivers clean and stable 12V for the audio section of the 6581 chip."you're mixing up the Core-Module (all std. 5V, as DIN/DOUT/...) with the SID-module (12v audio).Cheers,Michael ;)Edit: and don't feel ashamed... stryd is a very friendly person ;Dand we weren't really talking about you, we were just a bit amused about this philosophical question "how hot is too hot?" ;D... don't take it too serious!(and welcome to the forums, btw ;) ) Quote Link to comment Share on other sites More sharing options...
micah Posted November 6, 2006 Author Report Share Posted November 6, 2006 Please pardon my ignorance as this is all very new to me. This is also from http://www.ucapps.de/mbhp_sid.html:"If you don't want to use the C64 PSU, you can power both modules with the same transformer or wallwart for both modules. 14-15V AC (!!!before!!! the regulation unit) are required for a good and noiseless sound."I used a 16V AC transformer. I tested all the voltages and they are ok. 12v at the sid board, 5v at the sid PIC and 5v on the core. I feel like I'm not understanding a fundamental concept here in regards to the power supply.I also have a hard drive power supply that delivers both 5v/12v DC. would that be better?** i also just realized that my transformer is rated at 1000mA. could this also contibute to my overheating? Quote Link to comment Share on other sites More sharing options...
audiocommander Posted November 6, 2006 Report Share Posted November 6, 2006 I don't know. All I know is that the specs for the Core say, that it can take up to 10Vs. 12Vs should be okay, too.Have you measured your transformer if it really just provides 16Vs? Often these power units deliver much more than what is printed on the device... and if it provides 18V (eg., you're alot above the maximum of 14V)...However, as a hot regulator can also have other reasons (bridges, wrong solderings)... I would try powering the Core with normal 9Vs and see if it still gets hot.Regards,Michael Quote Link to comment Share on other sites More sharing options...
stryd_one Posted November 6, 2006 Report Share Posted November 6, 2006 Hehehe Yeh sorry if it sounded like I was teasing! I apologise, I'm just being silly. I'm good at that!I also completely missed that it was your 1st post, welcome aboard man :) Quote Link to comment Share on other sites More sharing options...
micah Posted November 6, 2006 Author Report Share Posted November 6, 2006 thanks for sending me your chat. yes, my 16V transformer is actually delivering 19V. Maybe I should go out and get a 14V 500ma as suggested.Or maybe I should just feed J2 a DC voltage and bypass the rectifier?? Hmmm... Quote Link to comment Share on other sites More sharing options...
audiocommander Posted November 6, 2006 Report Share Posted November 6, 2006 hey, nice to hear that :)I think some bucks for the right power supply are a good investment!Cheers!Michael Quote Link to comment Share on other sites More sharing options...
AndrewMartens Posted November 6, 2006 Report Share Posted November 6, 2006 For testing, I powered both my Core and SID modules from an unregulated "12V" DC power supply - in other words, 13.8V (which allows for the voltage drop before a 12V regulator). I could have done a dual-regulator (13.8 -> 9 -> 5) setup, but instead I ran the 7805 directrly from the DC supply voltage. Even with the whole unit (Core, SID and LCD) only drawing about 200 mA, the 7805 gets rather warm. I had a spare TO-220 heatsink around, so I threw it on there to help dissipate some of the heat.But supplying any more than 15V would be a real push... Quote Link to comment Share on other sites More sharing options...
micah Posted November 6, 2006 Author Report Share Posted November 6, 2006 Just bought a variable 9v-13v AC power adapter at radio shack. started it on 13V and worked my way down. It still makes sound and the noise goes down at 9V. Well, overall, I'm confused about the core/sid ratingsmaybe that will change once I connect the LCD, more modules etc. Is there any reason that I should avoid powering it at 9V ??? Quote Link to comment Share on other sites More sharing options...
Dave_Wheeler Posted November 10, 2006 Report Share Posted November 10, 2006 Hi,You need to consider what that poor little 7805 is being asked to do.If you have 19VAC, after the rectifier you will have close to the peak voltage which is 19/0.707=26.8VDC.The regulator will have to dissipate 21.8V. so for example if you are pulling 100mA your regulator has to dissipate 2.6W, however if the LCD backlight is on you are likely to be pulling more like 700mA which means you have to dissipate around 18W all of which is dissipated as heat. Just about enough to warm a cup of coffee :) :)Dave Quote Link to comment Share on other sites More sharing options...
HL-SDK Posted November 16, 2006 Report Share Posted November 16, 2006 R U SHUR?18 watts is a HELL of a lot to dissipate... Quote Link to comment Share on other sites More sharing options...
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